The control of weeds and other undesirable plants is important because weeds and other undesirable plants undermine the production of useful agricultural crops by inhibiting the production of foliage, fruit or seeds of these useful plants. The control of weeds on noncropped areas is also essential because, for example, weeds present a potential fire hazard and can give off allergy-aggravating pollen.
Plant growth regulation is also of economic importance, particularly in the area of harvest aid. The field of harvest aid utilization includes the defoliation of the crop plant; the desiccation of its leaves, stems, and other aerial organs; the control of late-season regrowth (e.g., for cotton); the promotion or inhibition of fruit or flower abscission; the concentration of crop maturity; and the enhancement of consumer-preferred quality factors.
Under normal conditions, many crop plants do not mature uniformly or in a timely fashion that would facilitate an efficient and optimum harvest, either due to equipment scheduling or weather considerations. Crops such as cotton, potato, sunflower, and seed legumes require either desiccation or defoliation before harvest can be effectively accomplished. For example, when cotton is not defoliated the leaves can interfere with mechanized picking apparatus which are frequently employed. Also, leaves can contaminate the cotton lint with trash or green stain, which reduces the quality of the fiber or reduces the efficiency of the ginning process. Likewise, potato vines need to be desiccated for efficient mechanical digging. In addition, upon desiccation of potato leaves and stems, the tuber skin matures and becomes less susceptible to damage from the digger and postharvest handling. Seed legumes and sunflowers are also mechanically harvested, and this process is facilitated if the leaves and stems are removed or desiccated. As with cotton and potato, such defoliation or desiccation also ripens the seed uniformly, accelerates the rate of seed maturation, and conditions the pod or head for easy harvest. In addition, the mechanical harvest of many fruit species, such as citrus, grape and olive, is routinely facilitated by the application of chemical abscission-inducing agents.
U.S. Pat. No. 4,746,352 describes certain 3-(5-carboxy-4-substituted-phenyl)-(thio)uracil esters useful for controlling weeds.
U.S. Pat. No. 4,812,164 describes certain ethers of 3-aryluracils useful as herbicides.
U.S. Pat. No. 4,943,309 describes a method for regulating the growth of plants using certain 3-carbonylphenyl uracil compounds.
U.S. Pat. No. 4,981,508 describes 1,4-benzoxazin-3-one substituted uracils useful as herbicides.
U.S. Pat. No. 5,176,735 describes a method for desiccating plants using certain 3-carbonylphenyl uracil compounds.
EP 0 438 209 A1 describes certain uracil derivatives useful as pesticides.
It is an object of this invention to provide novel aryl-substituted thionouracil derivatives for use in controlling weeds and other undesirable plants, and for use as desiccants and defoliants.
It is also an object of this invention to provide novel herbicidal, desiccant and defoliant compositions comprising the novel aryl-substituted thionouracil derivatives.
Additionally, it is a further object of this invention to provide a method for controlling undesirable plants using the novel aryl-substituted thionouracil derivatives.
It is a further object of this invention to provide a method for desiccating plants using the novel aryl-substituted thionouracil derivatives.
Finally, it is an object of this invention to provide a method for defoliating plants using the novel aryl-substituted thionouracil derivatives.